From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60680C4338F for ; Tue, 27 Jul 2021 01:12:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A02460F6D for ; Tue, 27 Jul 2021 01:12:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231819AbhG0AcP (ORCPT ); Mon, 26 Jul 2021 20:32:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231479AbhG0AcO (ORCPT ); Mon, 26 Jul 2021 20:32:14 -0400 Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19F64C061757 for ; Mon, 26 Jul 2021 18:12:42 -0700 (PDT) Received: by mail-pj1-x1030.google.com with SMTP id b1-20020a17090a8001b029017700de3903so1483903pjn.1 for ; Mon, 26 Jul 2021 18:12:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=5qmXa/hcXIxCYe084lwu8jX6+REyVQd0seK1gh4CDsc=; b=gXYgBUf2yED4498GlhqXM6R3mbM3uHPwNa0hh9M62c/NonqMa5DK1z/HAAaij1XvEk 4bjQWQZkGFbcV3bbwBcQtc2t8t5b4DqO1wBSQB8WZhoSUrFiACagGuu5l5LcDHH8cyQJ XlKwtY9hSte5Uj1yXvRb45tym1UhudQWV4qvyLAwW6fMJl2GfGj+nX8UsZoTvAYu/G24 jCTZBXmzEVlrDT+aIMDVzJZhsUREP56dsbLUZN22J+htzk3Nmi3hvJUG2CrDPvHjDZAb Qv739VGpSGR9WIn0u6A0gOXnTfQohRzxon//fXWHo8tNm+jq8gYZre9IBky3/UZmQYfj ZyEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=5qmXa/hcXIxCYe084lwu8jX6+REyVQd0seK1gh4CDsc=; b=W40cxI7MHS1HENRPfhbB3q9Ts0CCxM51016vE7lP4wq3Dgyab3etxArHHseFkaElBd 9OM01IqUZOnzmP/iO0rI5VI77WTIUn8UOPwujqjzvpDjVAwcMbiK6I0nJoMcBMchHhui wWyHlD76B4wRZ4RqdcxX2dNq9us+s9aMQWajt7zJJeeHBkVDI49NwjksuMzB11eOzakj CNPrrDSS43wKcsFvaN0iHsXrpdWnvJ8hWqBNAga2f6zKcsPqghiLDX4d4JmztaFSj7lJ TAPiVADOBT2hu94XQzFuXMzBwZ9p98j+IiddxvHA1KBadK5kHYyzPCWOkjxiX8Uu35u1 yGfw== X-Gm-Message-State: AOAM533d4qbuQadbJvklF11siHSNy6/nvboblClB0WcIz7OQ/T474wtK v+pJgw4E4QLlDfoxcCJtJ9o= X-Google-Smtp-Source: ABdhPJxs3CKx96v1IO9GW3YkSROPLrSpKODMa5a1kzmTb8sSaaYBNnDdy6RdfWmzCxzgZw+Rr8eOtQ== X-Received: by 2002:a63:f959:: with SMTP id q25mr21278198pgk.52.1627348361573; Mon, 26 Jul 2021 18:12:41 -0700 (PDT) Received: from [0.0.0.0] ([150.109.126.7]) by smtp.gmail.com with ESMTPSA id gk5sm698890pjb.51.2021.07.26.18.12.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Jul 2021 18:12:41 -0700 (PDT) Subject: Re: [PATCH bpf-next] libbpf: add libbpf_load_vmlinux_btf/libbpf_load_module_btf APIs To: Andrii Nakryiko Cc: bpf , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Yonghong Song , john fastabend References: <20210724051256.1629110-1-hengqi.chen@gmail.com> From: Hengqi Chen Message-ID: Date: Tue, 27 Jul 2021 09:12:38 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 7/27/21 6:49 AM, Andrii Nakryiko wrote: > On Fri, Jul 23, 2021 at 10:13 PM Hengqi Chen wrote: >> >> Add libbpf_load_vmlinux_btf/libbpf_load_module_btf APIs. >> This is part of the libbpf v1.0. [1] >> >> [1] https://github.com/libbpf/libbpf/issues/280 > > Saying it's part of libbpf 1.0 effort and given a link to Github PR is > not really a sufficient commit message. Please expand on what you are > doing in the patch and why. > Will do. >> >> Signed-off-by: Hengqi Chen >> --- >> tools/lib/bpf/btf.c | 24 +++++++++++++++++++++++- >> tools/lib/bpf/btf.h | 2 ++ >> tools/lib/bpf/libbpf.c | 8 ++++---- >> tools/lib/bpf/libbpf.map | 2 ++ >> 4 files changed, 31 insertions(+), 5 deletions(-) >> >> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c >> index b46760b93bb4..414e1c5635ef 100644 >> --- a/tools/lib/bpf/btf.c >> +++ b/tools/lib/bpf/btf.c >> @@ -4021,7 +4021,7 @@ static void btf_dedup_merge_hypot_map(struct btf_dedup *d) >> */ >> if (d->hypot_adjust_canon) >> continue; >> - >> + >> if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD) >> d->map[t_id] = c_id; >> >> @@ -4395,6 +4395,11 @@ static int btf_dedup_remap_types(struct btf_dedup *d) >> * data out of it to use for target BTF. >> */ >> struct btf *libbpf_find_kernel_btf(void) >> +{ >> + return libbpf_load_vmlinux_btf(); >> +} >> + >> +struct btf *libbpf_load_vmlinux_btf(void) >> { >> struct { >> const char *path_fmt; >> @@ -4440,6 +4445,23 @@ struct btf *libbpf_find_kernel_btf(void) >> return libbpf_err_ptr(-ESRCH); >> } >> >> +struct btf *libbpf_load_module_btf(const char *mod) > > So we probably need to allow user to pre-load and re-use vmlinux BTF > for efficiency, especially if they have some use-case to load a lot of > BTFs. > Should the API change to this ? struct btf *libbpf_load_module_btf(struct btf *base, const char *mod) It seems better for the use-case you mentioned. >> +{ >> + char path[80]; >> + struct btf *base; >> + int err; >> + >> + base = libbpf_load_vmlinux_btf(); >> + err = libbpf_get_error(base); >> + if (err) { >> + pr_warn("Error loading vmlinux BTF: %d\n", err); >> + return base; > > libbpf_err_ptr() needs to be used here, pr_warn() could have destroyed > errno already > OK. >> + } >> + >> + snprintf(path, sizeof(path), "/sys/kernel/btf/%s", mod); >> + return btf__parse_split(path, base); > > so who's freeing base BTF in this case? > Sorry, missed that. But if we change the signature, then leave this to user. >> +} >> + >> int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx) >> { >> int i, n, err; > > [...] >